The term "circulation" was widely used in French urban planning from the 1850s onwards to designate the flow of people, goods, information, traffic, communication, water, heat, light, waste, and air. The aim of this project was to explore the content of the term circulation and its physiological roots by focusing on three distinct yet complementary aspects. First, the project examined GE Haussmann’s urban reforms in Paris based upon the dual concept of a circulatory and respiratory system. This reform was achieved largely by improving the city’s circulation, meaning not only communication and transportation infrastructure but also sanitation reform or assainissement. The second aspect of this project dealt with the moral values assigned to circulation as related to vitality and health. The team of architects and engineers (A. Alphand, E. Belgrand, and ER Poubelle) involved in Paris’s urban reform made it a priority to improve the circulation of water, waste, and air by means of sewage systems, sidewalks, and plantings. The third and last aspect deals with circulation as a means to manage space and the flow of people. Efficient circulation was regarded as essential in both public spaces and in the economic sphere; thus, it is the space of circulation itself (including the material network as well as the regulations, the constraints and the limits assigned to the circulation of goods and people) that becomes the privileged object of government.